A method for enhancing oil recovery by combining miscible or near miscible gas flooding with Alkaline-Surfactant-Polymer (ASP) flooding to produce an enhanced Water-Alternating-Gas (WAG) flooding method is described. The ASP flooding may include individual and combination injections of alkaline, surfactant and polymer. Carbon dioxide may be used as a flood gas. Numerical simulations show that the present method may provide better oil recovery when compared with separate ASP or CO2 WAG flooding for different depositional environments, as a result of high micro and macro sweep efficiencies plus miscible gas flooding. A significant acceleration and improvement in recovery may be achieved with as small as a 10% pore volume ASP slug size.
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